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Signal/Pin
Pin Number
Name
PD7-0
82-75
PE
70
RDATA
54
RI2,1
97,87
RTS2,1
98,88
SIN2,1
99,89
SLCT
69
SLIN
73
SOUT2,1
100,92
STB
67
STEP
51
TC
25
TRK0
55
VDD
90,41
VSS
91,65,40, 15
WAIT
66
WDATA
49
WGATE
53
WP
57
WRITE
67
I/O and
Module
Group #
Parallel Port
I/O
Group 9
Parallel Port
Input
Group 2
Group 3
FDC
Input
Group 1
UART1
Input
Group 1
UART1,
Output
UART2
Group 12
UART1,
Input
UART2
Group 1
Parallel Port
Input
Group 2
Parallel Port
I/O
Group 8
UART1,
Output
UART2
Group 12
Parallel Port
I/O
Group 8
FDC
Output
Group 11
ISA-Bus
Input
Group 1
FDC
Input
Group 1
Power
Input
Supply
Power
Output
Supply
Parallel Port
Input
Group 2
FDC
Output
Group 11
FDC
Output
Group 11
FDC
Input
Group 1
Parallel Port
Output
Group 8
Parallel Port Data – These bidirectional signals transfer data to and from the peripheral
data bus and the appropriate parallel port data register. These signals have a high cur-
rent drive capability.
Paper End – This input signal is set high by the printer when it is out of paper. This pin
has an internal weak pull-up or pull-down resistor.
Read Data – This input signal holds raw serial data read from the Floppy Disk Drive
(FDD).
Ring Indicators (Modem) – When low, this signal indicates that a telephone ring signal
has been received by the modem.
The RI1 and RI2 pins have schmitt-trigger input buffers.
RI2 is multiplexed with DENSEL and available only in Two-UART mode.
Request to Send – When low, these output signals indicate to the modem or other data
transfer device that the corresponding UART1 or UART2 is ready to exchange data.
A Master Reset (MR) sets RTS to inactive high. Loopback operation holds it inactive.
RTS2 is multiplexed on pin 98 with IRSL1 and ID1, and available only in Two-UART
mode. RTS1 is multiplexed on pin 88 with BADDR1.
Serial Input – This input signal receives composite serial data from the communications
link (peripheral device, modem or other data transfer device).
SIN2 is multiplexed on pin 99 with ID3 and available only in Two-UART mode.
Select – This input signal is set active high by the printer when the printer is selected.
This pin is internally connected to a nominal 25KΩ pull-down resistor.
Select Input – When this signal is active low it selects the printer.
This signal is in TRI-STATE after a 0 is loaded into the corresponding control register
bit. Use an external 4.7 KW pull-up resistor.
This signal is multiplexed with ASTRB.
Serial Output – This output signal sends composite serial data to the communications
link (peripheral device, modem or other data transfer device).
The SOUT2,1 signals are set active high after a Master Reset (MR).
SOUT2 is multiplexed on pin 100 with IRRX2, IRSL0 and ID0, and is available only in
Two-UART mode.
SOUT1 is multiplexed on pin 92 with CFG0.
Data Strobe – This output signal indicates to the printer that valid data is available at
the printer port.
This signal is in TRI-STATE after a 0 is loaded into the corresponding control register
bit.
An external 4.7 KΩ pull-up resistor should be employed.
This signal is multiplexed with WRITE.
Step – This output signal issues pulses to the disk drive at a software programmable
rate to move the head during a seek operation.
DMA Terminal Count – The DMA controller issues TC to indicate the termination of a
DMA transfer. TC is accepted only when a DACK signal is active.
TC is active high in PC-AT mode, and active low in PS/2 mode.
Track 0 – This input signal indicates to the controller that the head of the selected
floppy disk drive is at track 0.
Main 5 V Power Supply – This signal is the 5 V supply voltage for the digital circuitry.
Ground – This signal provides the ground for the digital circuitry.
Wait – In EPP mode, the parallel port device uses this signal to extend its access cycle.
WAIT is active low. This signal is multiplexed with BUSY.
Write Data (FDC) – This output signal holds the write precompensated serial data that
is written to the selected floppy disk drive. Precompensation is software selectable.
Write Gate (FDC) – This output signal enables the write circuitry of the selected disk
drive. WGATE is designed to prevent glitches during power up and power down. This
prevents writing to the disk when power is cycled.
Write Protected – This input signal indicates that the disk in the selected drive is write
protected.
Write Strobe – In EPP mode, this active low signal is a write strobe. This signal is mul-
tiplexed with STB.
UP-5900VS CIRCUIT DESCRIPTION
5 – 41
Function
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